If one's opinion matters and he is influential, for example inside a company, we say that he has "something" within the company. I am sure there's a word for "something", but can't think of it right now.
This person I am trying to describe is not a leader, however he is very influential, e.g. he has been an old and respected member of a group, his opinion carries a lot of weight.
The word I'm looking for is not used very often